Verified answer

All of the dirty waste water which you send down the drains in your home or office is piped to a waste treatment plant to be cleaned into pure water which can be returned to a local river without harming the fish or other water life.

Part of the cleaning process involves a bacterial filter - which is home to millions of tiny bacteria (bugs) - these eat the filth in the water and let clean water pass out. If you pour something down your drain which is extremely poisonous or acidic to those bugs you may kill them and that part of the bacterial filter will stop working until it is recolonized by the bugs - which may take a long time during which the filter will be inefficient.

So the sentence is pointing this out to you to remind you to think about what you put down your drains, only normal dirty water from your home - some people for instance put car engine oil down their drains - this will kill those bacteria - so think before you dump things down your drain.

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Your town's wast water treatment plant uses bacteria (microscopic bugs) to break down the solids in your wast water. Adding chemicals to your waste water could harm, or kill these beneficial bugs.

Microscopic bugs which are known as bacteria are needed to decompose the waste in waste water. If you put strong chemicals in your drain it could kill the bacteria and thus stop the workings.

"Bugs" means the microorganisms that are naturally, or sometimes added, in the waste water that eat and break down the solids in the water. They can be killed by adding chemicals such as chlorine, detergents or caustics.